Hobbywing UBEC-3A (2-6S) User Manual

User manual of 3a ubec, 3 amp switch-mode ubec

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User Manual of 3A UBEC


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3 Amp Switch-Mode UBEC

1. Why do you need UBEC?

The UBEC is a switch-mode DC regulator separated from ESC (ESC---Electronic Speed

Controller for brushless/brushed motor), it will take high-voltage (5.5V to 26V) power from

your battery pack and convert it to a consistent safe voltage for your receiver, gyro and


For traditional speed controller with a built-in BEC, it will very likely have only a limited ability

to supply power to your receiver and servos without overheating. If you are using a

high-voltage battery pack or have heavy servo load, you should consult the ESC

specifications to determine what the stated recommendations or limitations are. In general, if

you are using a 4 cells lithium battery pack, or more than a 12 cells Nickel based battery pack,

you should consider using an UBEC because in such a case the built-in BEC of the ESC can

support only 2 servos, which means it is not suitable for RC helicopter and big aircraft.

2. Specification:


Output: 5V/3A and 6V/3A switchable


Ripple: <50mVp-p(@2A/12V)


Input: 5.5V-26V (2 to 6 cells Lipo battery pack, 5 to 18 cells NiMH battery pack)


Size: 51mm*16.6mm*8.5mm (length*width*height)


Weight: 11.5g

3. Features:


The UBEC is an advanced switching regulator with over-current and over-heat

protection function, and the maximum efficiency of the system is nearly 90%.


The small size and the light weight make it very convenient to use.


The comparison of linear BEC and switch-mode BEC: When using a lithium battery

pack more than 3S, a switch-mode BEC has much higher efficiency than linear BEC.

For a traditional linear BEC, For example, a 4S lithium battery pack has a

typical voltage of 14.8V, in order to let BEC output 5V/1A, the current flow

into the BEC is at least 1A, so the power on BEC is 14.8V* 1A=14.8W. But

the useful output power is only 5V*1A=5W, so the efficiency of the linear

mode BEC is just 5W/14.8W=33.8%, the redundant power 14.8W-5W=9.8W

changes to heat, which makes the BEC very hot.

For a switch-mode BEC in the above case, in order to let BEC output 5V/1A,

the current flow into BEC is only 0.38A (actual test data), so the power on

BEC is 14.8V* 0.38A =5.6W, and the efficiency of BEC is 5W/5.6W=89.3%.


Don’t worry about the polarity of battery pack. If the polarity is not correct, the UBEC
can’t work, but it will not be destroyed. What you need to do is just swap the battery
pack polarity.


A shield covers almost all the electronic components on PCB, and a ferrite ring is

attached with the output wires to decrease the electromagnetic interference.

4. How to use UBEC?


Important hint: Switch mode UBEC may cause some electromagnetic

interference to receiver, Please install the UBEC with a distance at least 5cm

away from the receiver.


When ESC HAS NOT built-in BEC

No change is needed for the ESC, just connect the input cables of UBEC with the

battery, and plug the output cable (connector) of the UBEC into one spare channel of

the receiver.






The color of trio wires:

white/red/black (from top to bottom)






When ESC HAS built-in BEC

You must disable the built-in BEC of the ESC, that is, you need to cut the red wire in the
trio of Rx (receiver) wires. Simply use a pair of wire cutters to remove a short section of
the red wire near the receiver connector, and insulate the cut wire with a bit of electrical

Suggestion: You can use a sharp
screwdriver to take the pin (with red wire)
out from the BEC connector of the ESC,
and then insulate it with a bit of electrical
tape for further use, so you

needn’t cut

the red wire by this method.










Cut the red wire in the trio of

receiver wires